It is a requirement of a wound dressing that it should protect the wound from exterior foreign body invasion etc whilst promoting healing of the wound through maintaining a desirably moist and warm environment about the wound.
Traditionally, wound dressings have comprised a non-woven web of material such as cotton wool with gauze to provide a pseudo non-adherent coating which will allow wound exudate to be absorbed whilst inhibiting incorporation of the actual wound dressing in the regenerated skin tissue of the wound.
There are readily apparent limitations with a traditional cotton wool wound dressing with regard to the amount of exudate absorption per weight of wound dressing and the bulk of this type of dressing. It will be appreciated that ideally wound dressings should be replaced as few times as possible in order to ensure the wound remains warm and moist. There is a significant temperature drop about the wound site upon each occasion that the wound dressing is removed, however, and with previous wound dressings it was necessary to replace the dressing quite frequently particularly with burns as the dressing quickly became saturated with exudate.
It is known to provide multi-component wound dressings which comprise two or more absorbent layers in order to enhance absorption capacity. One or more of the layers being replaceable when saturated. Examples of such multi-component wound dressings are given in U.S. Pat. No. 5,167,613 (The Kendall Company) and WO 93/07841 (Cummings).
Although these multi-component dressings may include hydrophobic fibres and gells, the objective is to limit wound trauma when removing the replaceable absorbent layers. Thus, the absorbent layers tend to be highly incapsulated and present several filmic barrier layers to the wound site greatly reducing the suitability of such dressings for highly exuding wounds. These multi-component dressing are most suitable for long term use in relatively slowly exuding wounds.
More recently alginate and polysaccharide fibres have been investigated for wound dressings. However, these fibres can be too aggressive with respect to the rate of exudate absorption and also may cause irritation about the wound site. Furthermore, some types of absorbent fibre may present toxicology and sterilisation problems.